From 2adc552cb5ee28d3cf8db2d2a081dfd68178fedc Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Mon, 2 Feb 2026 11:30:21 -0500
Subject: [PATCH 56/98] FIXME: add GCC_DIAGNOSTICS_IGNORE_DUMPDIR

---
 gcc/doc/invoke.texi    | 30 +++++++++++++++++++++++++++---
 gcc/opts-diagnostic.cc |  6 +++++-
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 42040d462368..39c4e6b4e2c3 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -6343,7 +6343,8 @@ The default is @samp{text}.
 @cindex diagnostic output formats, sarif-file
 The @samp{sarif-stderr} and @samp{sarif-file} formats both emit
 diagnostics in SARIF Version 2.1.0 format, either to stderr, or to a file
-named @file{@var{source}.sarif}, respectively.
+named @file{@var{source}.sarif}, respectively.  See also
+@env{GCC_DIAGNOSTICS_IGNORE_DUMPDIR}.
 
 @opindex fdiagnostics-add-output
 @item -fdiagnostics-add-output=@var{DIAGNOSTICS-OUTPUT-SPEC}
@@ -6409,7 +6410,7 @@ Supported keys for the @code{sarif} scheme are:
 @item file=@var{FILENAME}
 Specify the filename to write the SARIF output to, potentially with a
 leading absolute or relative path.  If not specified, it defaults to
-@file{@var{source}.sarif}.
+@file{@var{source}.sarif} (see also @env{GCC_DIAGNOSTICS_IGNORE_DUMPDIR}).
 
 @item serialization=@r{[}json@r{]}
 Specify the serialization format to use when writing out the SARIF.
@@ -6452,7 +6453,7 @@ Add an embedded <style> to the generated HTML.  Defaults to yes.
 @item file=@var{FILENAME}
 Specify the filename to write the HTML output to, potentially with a
 leading absolute or relative path.  If not specified, it defaults to
-@file{@var{source}.html}.
+@file{@var{source}.html} (see also @env{GCC_DIAGNOSTICS_IGNORE_DUMPDIR}).
 
 @item javascript=@r{[}yes@r{|}no@r{]}
 Add an embedded <script> to the generated HTML providing a barebones UI
@@ -37503,6 +37504,29 @@ attempt to open that file and write the information there.
 The precise content and format of the information is subject to change;
 it is intended for use by GCC developers, rather than end-users.
 
+@vindex GCC_DIAGNOSTICS_IGNORE_DUMPDIR
+@item GCC_DIAGNOSTICS_IGNORE_DUMPDIR
+When outputing files for diagnostics (such as with
+@option{-fdiagnostics-add-output=sarif} or
+@option{-fdiagnostics-format=sarif-file}), the compiler will by default
+select an output path that respects the dump directory, either when
+set implicitly by the driver to match that of the output file, or
+provided explicitly via @option{-dumpdir}.
+
+For example, with
+@smallexample
+gcc \
+  -o build-dir/foo.o \
+  -fdiagnostics-add-output=sarif
+  foo.c
+@end smallexample
+the compiler will write the SARIF to @file{build-dir/foo.c.sarif}.
+
+However in GCC 13, 14, and 15, SARIF output did not respect the dump
+directory, and instead wrote the SARIF to @file{foo.c.sarif}.  Setting
+@env{GCC_DIAGNOSTICS_IGNORE_DUMPDIR} restores the old behavior, for
+compatibility with build systems that expect this.
+
 @vindex GCC_COMPARE_DEBUG
 @item GCC_COMPARE_DEBUG
 Setting @env{GCC_COMPARE_DEBUG} is nearly equivalent to passing
diff --git a/gcc/opts-diagnostic.cc b/gcc/opts-diagnostic.cc
index 8d4bc1438b2d..61438614a3e5 100644
--- a/gcc/opts-diagnostic.cc
+++ b/gcc/opts-diagnostic.cc
@@ -186,7 +186,11 @@ get_diagnostic_file_output_basename (const gcc_options &opts)
      the dump dir to the dump base name.  If so, make a prepended copy
      now and use it.  */
   if (opts.x_dump_base_name
-      && ! opts.x_dump_base_name_prefixed)
+      && ! opts.x_dump_base_name_prefixed
+      /* In GCC <= 15 we failed to prepend the dumpdir.
+	 Support the old behavior if GCC_DIAGNOSTICS_IGNORE_DUMPDIR is set
+	 in the environment.  */
+      && !getenv ("GCC_DIAGNOSTICS_IGNORE_DUMPDIR"))
     if (const char *prepended_dump_base_name
 	  = maybe_prepend_dump_dir_name (opts))
       /* Allocated in opts_obstack.  */
-- 
2.49.0